THE RELATION OF DIET TO DISEASE 419 
production of organic acids is a frequent occurrence. 
Putrefactive types are very rare except with pyloric 
stenosis, a condition which favors excessive fermentation 
by diminishing the tone and motility of the stomach and 
the amomit of hydrochloric acid. This condition is 
further increased by excessive carbohydrate food. In 
general the products of fermentation tend to restrict 
putrefaction, yet both may be operative. In the small 
intestines, bacteria are always present because of the pro- 
tein richness of secretions, the rapid digestion of food and 
the slight or ineffectual antiseptic properties of intestinal 
juice, bile and pancreatic secretions. The putrefactive 
bacteria rapidly increase and decompose any protein that 
is miabsorbed — a process most marked in the colon 
because its shape and position favor stasis or slow move- 
ment of its contents. In general the greater the amount 
of unabsorbed and digestible protein and the longer the 
material stays in the intestinal tract, the greater the 
putrefaction. The meat-eating animals develop Gram- 
negative bacilli, while the carbohydrate-eaters show a 
predominance of Gram-positive types. 
Ingested food never contains the enormous amount of 
bacteria found in the feces. The alimentary tract with its 
contents forms a most efficiently combined incubator and 
culture medium, in which bacterial growth exceeds that of 
any known location both in intensity and complexity. The 
range of reaction and composition of nutritive substances 
at different levels of the intestinal tract is such that a 
great variety of bacteria capable of growth at body tem- 
perature develop. The prominent types that appear in 
the flora of each order of mammals are fairly constant 
in their occurrence. They depend primarily on food 
ingested, and show well marked seasonal variations, 
dependent again on changes in food. Faulty feeding may 
itself give rise to a toxic condition of the gastrointestinal 
tube, and thus often prepares this soil for the develop- 
ment of organisms. 
